Copper/Boron is essential in transportation of carbohydrate through phloem tissues.

Explanation

**Step-by-Step Solution:**

1. **Understanding the Role of Copper and Boron**: Copper and Boron are essential micronutrients in plants. They play a critical role in various physiological processes, including the transportation of carbohydrates.

2. **Phloem Function**: The phloem is the vascular tissue responsible for the transport of nutrients, particularly carbohydrates produced during photosynthesis, from the leaves to other parts of the plant.

3. **Copper's Role**: Copper is involved in several enzymatic reactions and is crucial for the synthesis of certain proteins that facilitate the movement of carbohydrates through the phloem.

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